Musicality (US$9.99) offers one-app access to Pandora, Last.fm, and Grooveshark streaming music services. What's more, it adds in extra features that integrate with Growl notifications (so you can immediately see what song is playing, even when the app itself is hidden) and AirPlay. It's this latter feature that had me asking to take a look at the app. With AirPlay, you can stream your music from your computer to any AirPort Express, AirPlay-enabled speaker system, or Apple TV.